Centrifugal separator



R. E. LAPHAM CENTRIFUGAL SEPAHATOR Filed Dec. 24

Patented Apr. 17, 1923.

RALPH E. LAPHAIVI, OF OAKLAND, CALIFORNIA.

CENTRIFUGAL SEPARATOR.

Application filed December 24, 1921. Serial No. 524,677.

To all whom it may concern:

Be it known that I, RALPH E. LAPHAM, citizen of the United States, residing at Oakland, in the county of Alameda and State of California, have invented certain new and useful Improvements in Centrif ugal Separators, of which the following is a specification.

The present invention relates to certain new and useful improvements in centrifugal separating machines of that general type which is disclosed by Patent #1336368 which was granted to me on April 13, 1920. The improvements relate more particularly to a novel means for conserving the supply of the mercury or other mobile separating medium and preventing loss of the mercury with the tailings.

In the operation of the centrifugal sepa rating machines, a smooth, even flow of the mercury or mobile separating medium is es sential, and any violent movement of the mercury must be avoided since one of the characteristics of mercury is that it is readily floured or broken up into very fine globules when brought forcibly against an obstruction, and in this condition it would be inevitable that many of the globules would be carried away with the tailings. It is also important to provide for a complete separation of the mercury and the tailings befor the latter are carried around the overflow rim and deposited in the discharge launder. Any appreciable loss of the mercury with the tailings might more than ofi'.

set the value of the precious metals or materials recovered by the separator, so that in a commercial machine of this character it is necessary that the supply of mercury or mobile separating medium be very carefully andeflectively conserved and guarded against loss. With a view to accomplishing this resuit the present invention provides an aux iliary mercury return which is located adjacent to the overflow edge and is of a peculiar nature so that the mercury can flow freely through the passage although sand is effectively excluded therefrom.

With these and other objects in view, as will more fully appear as the description proceeds, the invention consists in certain arrangements and combinations of the parts, the novel features whereof are pointed out in the appended claims.

For a full understanding of the invention reference is to be had to the following de scription and accompanying drawings, in which;

Figure 1 is an enlarged vertical sectional view through the upper edge of the bowl of a centrifugal separating machine which is constructed in accordance with the invention.

Figure 2 is a fragmentary detail view of one of the superposed plates which are fitted in the auxiliary return passage for the mercury.

Corresponding and like parts are referred to in the following description and indicated in all of the views of the drawings by like reference characters.

The invention of this application is intended to be embodied in a centrifugal separating machine of the general 'ype disclosed by Patent aft-1,336,968 which was granted to me on April 13, 1920, and also of the type shown by my copending application Serial #401,883, filed August 7, 1920. In view of the disclosures in the prior patent and application, it is not thought necessary to illustrate and describe in detail the special mounting of the revolving bowl. On the present drawings the numeral 1 designates the upper edge portion of a bowl, which may be mounted in any suitable or conventional manner, the details of the mounting being immaterial and forming no part of the present invention. The interior of the bowl is provided with a wall 2 which is spaced from the bowl to provide a return passage 3. In the operation of the separator the bowl is caused to revolve at a high rate of speed and the mercury or other mobile separating medium circulates upwardly over the face of the wall 2 in a thin stream which is in an amalgamated engagement therewith, and returns by way of the passage 3. The sand or other material being operated upon circulates upwardly over the mercury 4, and

the centrifugal force produced by the rapid rotation of the bowl is such as to cause an effective separation of the heavier values from the sand. These heavier values have a specific gravity greater than the mercury and are collected. in pockets 5, formed in the wall tube. The sand which has lower specific gravity than the mercury circulates upwardly over the outer face of the mercury and is ultimately discharged over the 'rim at the upper edge of the bowl.

The wall 2 and bowl 1 are preferably formed, pf ome material, such copper or be clear from what has already been said.

.members such. as screws 7.

The upper edge of the bowl 1 is provided with an overflow rim 6, which is shown as rigidly secured in position by fastening The overflow rim is provided in the usual manner with a rearwardly extending flange 6 which tends to direct the ta-ilings as they are discharged from the bowl into the launder 8 of a fixedly mounted casing 9. A flange 10 which is formed in connection with the overflow rim projects downwardly within the bowl and assists in retaining an angle iron ring 1]. in position. The abutting edges of these two members may be constructed to have an overlapping relation. as indicated at 12, and packing 13 may be interposed. between the members to provide a tight joint which will effectively prevent the escape ot the mercury or mobile separating medium through the joint. As inc icated on the drawing the ring): 11 and positioning flange 10 of the overflow rim are received within a rabbeted portion at the upper edge of the bowl, so that the ring 11 is clamped in position between the lower edge of the flange 10, and the shoulder 14 at the bottom of the rabbeted edge of the bowl.

One of the flanges oil the angle iron ring 11 projects outwardly into the bowl and cooperates with the overflow rim 6 to provide a pocket A within which the mercury or mobile separating; medium collects. The depth of the mercury in this pocket A is determined by the extent the ring 11 projects outwardly from the bowl. and it will be obvious that when the pocket is filled with mercury the circulation of mercury throughthe machine will cause the mercury to overflow the ring); 11 and be directed around the edge and lower face thereof into the return passage 3.

Applied to they upper edge of the wall 2 is a guide ring; 15, which is shown as havingan angle iron formation. One of the flanges of the guide ring :torms in effect a continuation of the wall 2. while the other flange of the guide ring; extends into the mercury pocket A and serves to guide and to direct the upwardly circulatinr': stream oi? mercury 'l'rom'the wall 2 into the mercury pocket. The overflow rim 6 must of course project into the bowl a greater amount than the ring 11 so that the mercury collecting in the pocket A will overflow the said ring l1 and be carried into the return passage 3 before it has an opportunity to escape around the overflow rim with the sand or ta-ilings as they are discharged from the machine. I

Most of the mercury or mobile separating medium will circulate directly through the pocket A by passing through the space be tween the bottom of the overflow rim and the top of the guide ring 15. A. certain amount of the mercury or separating medium however will circulate through what may be termed an auxiliary return passage which is provided in the overflow rim, and which constitutes the essential features of the present invention. This auxiliary return passage for the mercury is of a peculiar and special character and em bodies novel features of construction where by a free passage is provided for the mercury although sand and foreign matter are most effectively excluded and prevented from following the mercury.

The inner edge of the overflow rim is cut away or recessed to provide a space within which a series of super 'iosed annular plates or rings 16 are fitted. Thor. plates are arranged transversely with respect to the axis upon which the bowl rotates. and the inner edges thereof form a portion of the inner face of the overflow rim. These annulmplates 16 are formed of some ms. .rial for which the separating medium has an E flnity. l l here mercin'y is used the plates are preferably of soft sheet copper or of a suitable copper alloy. Sheet copper oi? about 2st gigaugre in thickness will give satisfactory results. and each of these plates is preterm bly silver plated on all sides betore the plates are assembled. Each joint between the plates will then have two silvered surlaces and allowing for slight irregularities of the plates, there will be a space oi zip-- proxin'iately one thousandth of an inch between the plates. Owing to the wel known fact that mercury has an aflinity tor such plates and readily amalgamates therewith. it will be uinlerstcod that mercury under pressure will readily pass between the plates. although all of the sand and. tailin will be excluded. The assembled plates "Form in effect a porous body which is pcrvious to the mercury and inuiervious to the sand and tailings. This porous body nuctically lilters the mercury so as to eliminate all impurities and fo eign matter therefrom. =l the aflinily ot' the a-maloaniated p re for the mercury is such that it is iin iiossible for any of the mercury to escape with the tailings and the supply of mercury is conser ed in a most cilectbre manner.

The plates 1.6 ma be held in position within. the recessed portion of the overflow lill rim in any suitable manner. In the specific construction illustrated by the drawing the lower Wall of this recess is in the form of a separate ring 18 which has a threaded connection as indicated at 19.140 the flange 10 of the overflow rim. After the plates 16 have been assembledv within the recess the ring 1.8 is placed in position and screwed against the plates to confine them in the desired manner.

The plates 16 are formed with corresponding openings 20 and the said plates are assembled with these openings in registry with each other and also in registry with openings 21 in the ring 18. These openings thus provide passages through which the mercury circulating between the plates 16 can enter the pocket A. The interstices be tween the plates 16 and the openings 20 and 21 thus provide what is in effect an auxiliary passage for conveying a part of the mercury into the pocket A and thence back to the return passage 3. .This is accomplished without any abrupt or sudden movement of the mercury and the mercury: passing through the auxiliary passage is in effect filtered so that all impurities are removed therefrom. It will be noted that the inner edge of the overflow rim 6 has the face thereof disposed at a slight angle and that the inner edges of the plates 16 terminate flush with the angular face of the rim, and are finished so as to provide a smooth face. This face may be arranged at any suitable angle, although in the machine illustrated it has been found that an angle of 10 degrees to the vertical gives satisfactory re sults. The depth of the mercury which collects in the pocket A is determined by the amount the ring 11 projects inwardly from the bowl, as previously mentioned. and the arrangement between the parts is such that the surface of the mercury inthe pocket extends upwardly over the inclined face of the overflow rim to 'a point intermediate the upper and lower edges of the exposed por tic-n of the porous or mercury filtering body composed of the assembled plates 16. ()wing to the slight angular inclination of this wall and the afiinity of the mercury for the edges of the silyered plates. the depth of the inercury upon the inclined face of theoyerflow rim will gradually decrease upwardly and finally merge into the surface provided by the edges of the silyered. plates Themercurv really thins out to practically nothing. andv leaves no abrupt or well defined ending at its uppermost edge. At this point there is no appreciable depth of either sand or mercury and. no abrupt edge of the bowl for the sand and tailings to strike against in their upward passage. Under these conditions the sand and railings will be completely separated from the mercury and will pass freely over the edge of thecverfiow rim.

In this connection it may be mentioned that the water that passes through the machine with the sand or material being treated is suilicient to wash out the sand readily as it passes over the edge of the overflow rim and the sand is washed out as fast as it comes along without being permlitted to accumulate or become of any thickness. As the mercury flows to the very uppermost edge of the bank of mercury it enters the interstices between the plates and there is thus a continuous circulation of the mercury, so that this body of mercury is always fresh and alive and is prevented from becoming a still or stagnant mass of mercury.

It will be remembered that the mercury or other mobile separating medium is acted upon strongly by centrifugal force owing to the rapid rotation of the bowl. so that there is a. constant outward pressure of the mercury against the faces of the wall 2 and bowl 1. The upper portion or zone of the mercury within the pocket A is also held forcibly against that portion. or" the overflow rim 6 which is formed of the exposed edges of the plate 16, and the pressure of the mercury against the plates is suiiicient to cause it to pass freely between the plates in an amalgamated engagement therewith.

The thin upper cury is in strong amalgamated connection with the edges of the silyered plates 16. so that any loss of the mercury with the tailingrs is ayoided, and impurities of the mercury and of the ore will pass over the bank of mercury and out of the machine with the tailings due to the fact that they have a lower specific gravity than the pure 1nercury. The mercury is thus continually filtered or purified. as it passes through the machine. and the ultimate separation of the mercury and sand which takes place at the crises of the plates 16 where they form the inner wall of the overflow rim is of such a positive character that the machine can be operated without any real. or a preciable loss of the mercury. The lower face of the ring 18 may he recessed. as shown. and the upper edge of the guide ring 15 formed with a projection 15 entering the recess. thereby providing a baffle arrangement which is of assistance in excluding sand and railings from the mercury in the pocket and obtain an cren flow of the n'iercury through the pocket before it overflows the rin 11 and is carried thereby to the return passage 3. The mercury circuit may be produced and maintained in any suitable manner. and means for doing: this are hilly disclosed in my prior patent and copendine' application to which reference has previousl been made. For the purpose of illustration one particular hysical embodiment of the invention has been illustrated and described in detail, although it will be unedge of the bank of mer- .1

ters Patent is 1. In a separating machine having a mercury circuit, filtering means interposed in a portion of the circuit and including a metallic filtering body through which the mercury flows in an amalgamated engagement.

2. In a centrifugal separating machine through which a mobile separating medium travels in a circuit, filtering means interposed in a portion of the circuit and arranged so that the pressure caused by centrifugal force tends to force the medium through the filter.

3. In a separating machine having a mercury circuit, filtering means interposed in a portion of the circuit and including a series of plates between which the mercury flows in an amalgamated engagement.

4. In a centrifugal separating machine through which mercury travels in a circuit, filtering means interposed in a portion of the circuit and comprising a series of plates between which the mercury passes in an amalgamated engagement, the filter being arranged so that pressure caused by centrifugal force tends to force the mercury through the filter.

5. In a separating machine through which a mobile separating medium travels in a circuit, a main passage and an auxiliary passage being provided between the separating portion of the circuit and the return portion of the circuit, and filtering means arranged in the said auxiliary passage.

6. In a centrifugal separating machine through which a mobile separating medium travels in a circuit, a main passage and an auxiliary passage being provided between the separating portion of the circuit and the return portion of the circuit, and. filtering means arranged in the said auxiliary passage.

. '7. In a centrifugal separating machine through which mercury travels in a circuit, a main passage and an auxilia y passage being provided between the active portion of the circuit and the return portion of the cir cuit, and a filtering body arranged in the said auxiliary passage with the out 1? face thereof exposed within the machine so that a portion of the mercury'is held in a forcible engagement therewith by centrifugal force.

8. In a centrifugal separating machine through which mercury is caused to travel in a circuit, a filtering body interposed between the active portionof the circuit and the return portion of the circuit and having the face thereof exposed within the machine so that the mercury at that part of the machine is held in a forcible engagement with the filter by the action of centrifugal force.

9. In a centrifugal separating machine through which mercury is caused to travel in a circuit, a filtering body interposed between the active portion of the circuit and the return portion of the circuit, said filtering body being formed of a series of plates having edge portions thereof exposed within the machine and arranged so that the merc-ury'at that portion of the machine is held forcibly in engagement with the edge portion of the plates by the action of centrifugal force, the mercury circulating be tween the plates in an amalgamated engagement therewith.

10. In a centrifugal separating machine through which mercury is adapted to travel in a circuit, a filtering member interposed between the active portion of the mercury circuit and the return portion of the said circuit, said filtering member having one side thereof exposed within the machine and arranged at an angle to the axis thereof, means being provided for causing the mercury to engage the inclined face of the filter and the pre'ssureproduced by the action of centrifugal forcetending to force the mercury through the filter.

11. In a separating machine, a rotatable bowl having walls over which a mobile separating medium is adapted to circulate in a continuous stream when the machine is in operation, said bowl being also provided with a return passage for the separating medium, an overflow rim for the bowl, and a member arranged adjacent the upper edge of the overflow rim and exposed within the bowl, said member being pervious to the separating medium and impervious to the tailings, the pressure produced by centrifugal force tending to force the separating medium through the said member.

12. In a centrifugal separating machine, a rotatable bowl having walls over which amobile separating medium is adapted to circulate in a continuous stream when the ma- I chine is in operation, said bowl also provided with a return passage for the separating medium, an overflow rim, and a member arranged adjacent the upper edge of the overflow rim with the face thereof exposed upon the interior of the bowl, said member ed to circulate in a continuous stream when the machine is in operation, said bowl being also provided with a return passage for the separating medium, an overflow rim, and a member imbedded in the overflow rim and exposed at the inner face thereof so that the tailings must pass over the same, said member being pervious to the separating medium and impervious to the tailings and the face thereof being arranged at an angle to the axis of the bowl so that pressure produced by centrifugal force will tend to drive the separating medium through the member, means being provided for convey ing the portion of the separating medium which passes through the said pervious member to the return portion of the circuit.

1%. A centrifugal separator, including a rotatable bowl having walls over which mercury is adapted to circulate in a continuous stream when the machine is in operation, said bowl having a return passage for the mercury, an overflow rim for the bowl, and a series of plates imbedded in the overflow rim with edge portions thereof exposed at the inner face of the rim, said plates being formed of material for which mercury has an affinity and the exposed edges of the plates forming a wall which is pervious to the mercury and impervious to the tailings.

15. A centrifugal separator including a rotatable bowl having walls over which mercury is adapted to circulate in a continuous stream when the machine is in operation, said bowl being also provided with a return passage for the mercury, an overflow rim for the bowl, a series of plates embedded in the overflow rim and having edge portions thereof exposed at the inner face of the overflow rim, said inner face of the overflow rim being arranged at an inclination to the axis of the bowl and the exposed edges of the plates forming a zone in this inclined face of the overflow rim which is pervious to the mercury and impervious to the tailings, means being provided for conveying the portion of the mercury which passes through the plates to the return passage.

16. A centrifugal separator including a rotatable bowl having walls over which mercury circulates in a continuous stream when the machine is in operation, said bowl being also provided with a return passage for the mercury, an overflow rim having an inner face which is inclined to the axis of the bowl, means for providing a pocket of mercury at the upper edge of the bowl which is of such a depth that the surface of the mercury in the pocket extends partially over the inclined face of the overflow rim, and a member imbedded in the overflow rim and exposed at the inclined face thereof,

said member being pervious to mercury and impervious to the tailings.

17. In a centrifugal separting machine, a rotatable bowl having walls over which mercury circulates in a continuous stream when the machine is in operation, an overflow rim havii'ig an inner face formed with a portion which pervious to mercury and impervious to the railings, and means for providing a pocket within which the mercury collects, the mercury of the pocket extending over the inner face of the overflow rim in engagement with the portion thereof which is pervious to the mercury.

18. A centrifugal separator including a rotatable bowl having walls. over which mercury is adapted to circulate in continuous stream when the machine is in operation, an overflow rim having an inner face which is arranged at an angle to the axis of the bowl and a portion of which is pervious to the mercury and impervious to the tailings, said portion of the bowl being formed of a substance which has an affinity for mercury so that the mercury will be in an amalgamated engagement therewith, and means for providing a mercury pocket adjacent the overflow rim so that the surface of the mercury in the pocket extends over the inclined inner face of the overflow rim into engagement with the said pervious portion thereof.

19. A centrifugal separator including a rotatable bowl having walls over which mercury is adapted to circulate in a continuous stream when the machine is in operation, an overflow rim having the inner face thereof recessed, a series of superposed plates fitted in the recess with the edges thereof exposed at the inner face of the overflow rim, said plates being formed of material for which mercury has an aflinity so that the mercury will circulate between the same in an amalgamated engagement therewith, and means for providing a men c-ury pocket adjacent the overflow rim, the mercury of the pocket extending over the inner face of the overflow rim into en ag ment with the exposed edges of the p ates.

20. A centrifugal. separating machine including a rotatable bowl having walls over which mercury circulates in a continuous stream when the machine is in operation, an overflow rim having an inner face which is inclined to the axis of the bowl, a series of plates imbedded in the overflow rim with edge portions thereof exposed at the inner.

face of the rim and forming a portion of the inclined face thereof, said plates being formed of a material which has an afflnity with mercury and the exposed edges there of forming a wall which is pervious to mercury and impervious to the tailings, and means for providing a mercury pocket ad- IOU Lnnii jacent the overflow rim, the surface of the mercury in the pocket extendlng over the inclined face of the rim into engagement cuit and the return portion of the circuit, said filtering body being formed of a series of plates having edge portions thereof exposed Within the machine and arranged so that the separating medium is held forcibly in engagement with the edge port-ions of the plates by the centrifugal force of the machine.

In testimony whereof I asliix my sig- 20 nature.

RALPH E LAPHAMQ 

